Brain proteoglycans play an important role in learning and memory processes and in the pathogenesis of neurodegenerative disease. Brain proteoglycans in Wistar rats and early aging OXYS rats at the age of 1, 2, and 14 months were compared. Proteoglycan content in OXYS rats aged 1 and 2 months is 2-fold lower than in Wistar. The content of proteoglycans 7-fold decreases in Wistar and OXYS rats with age at the expense of heparan sulfates and chondroitin sulfates and by the age of 14 months, the difference between the strains is leveled. These results indicate that cognitive and emotional disorders observed in OXYS rats by the age of 3 months develop against the background of significant changes in the content and composition of proteoglycans.